The present invention relates generally to the art of gas pressure driven fluid pumps. More particularly, the invention relates to such a pump utilizing a snap-acting rotary valve to control gas ports.
Condensate removal systems in steam piping arrangements often utilize gas pressure driven pumps that function without electrical power. As described in U.S. Pat. No. 5,938,409 to Radle (incorporated herein by reference), such a pump will typically have a tank with a liquid inlet and liquid outlet. The liquid inlet and liquid outlet, which are located near the bottom of the tank, will be equipped with an inlet check valve and an outlet check valve to permit liquid flow only in the pumping direction. A pair of valves interconnected by a snap-acting linkage control a gas motive port and a gas exhaust port.
The pump operates by alternating between a liquid filling phase and a liquid discharge phase. During the liquid filling phase, the motive port is closed while the exhaust port is open. A float connected to the snap acting linkage rises with the level of liquid entering the tank. When the float reaches an upper crossover point, the linkage snaps over to simultaneously open the motive port and close the exhaust port. As a result, the pump will switch to the liquid discharge phase.
In the liquid discharge phase, steam or other motive gas is introduced into the pump tank through the motive port. The motive gas forces liquid from the tank, thus causing the float to lower with the level of the liquid. When the float reaches a lower crossover point, the linkage snaps over to simultaneously open the exhaust port and closes the motive port. As result, the pump will again be in the liquid filling phase.
While the snap-acting linkage used in gas pressure driven pumps of the prior art has generally functioned well, there exists room in the art for additional snap-acting valve arrangements.
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.
In one aspect, the invention provides a gas pressure driven fluid pump comprising a pump tank having a liquid inlet and a liquid outlet. A float, carried within the interior of the pump tank, is operable to move between a low level position and a high level position. A snap-acting valve is operatively connected to the float.
The snap-acting valve has a rotatable port member that moves so as to switch to exhaust porting when the float falls to the low level position. The port member further switches to motive porting when the float rises to the high level position. As a result, fluid filling the pump tank causes the float to rise from the low level position to the high level position during exhaust porting. Fluid exiting the pump tank causes the float to fall from the high level position to the low level position due to introduction of motive gas during motive porting.
In some exemplary embodiments, the valve comprises an actuator member connected to the float so as to directly rotate as the float moves between the low level and high level positions. Also provided is a mechanism operatively interconnecting the actuator member and the port member such that rotation of the actuator member will cause selective rotation of the port member. Often, the mechanism interconnecting the actuator member and the port member may comprise at least one spring extending between the actuator member and the port member. For example, the mechanism may comprise a plurality of spaced apart springs extending between the actuator member and the port member.
Preferably, the actuator member and the port member of the valve may rotate about a common axis. For example, the float may be connected to the actuator member by an axial shaft rotating about the common axis so as to cause rotation of the actuator member.
Exemplary embodiments are contemplated in which the port member defines first and second fluid passages which are moved into and out of registry with respective motive and exhaust ports when the port member rotates. In such embodiments, the motive and exhaust ports may be defined in a fixed surface. The port member and the fixed surface are preferably juxtaposed in face-to-face contact.
Other aspects of the present invention are achieved by a snap-acting valve comprising an actuator member movable between a first position and a second position. A port member defining a first flow passage is also provided. The port member is configured to move between an open position that allows flow through the first flow passage and a closed position that prevents flow through the first flow passage. Also provided is a mechanism interconnecting the actuator member and the port member such that the port member snaps over to the open position when the actuator member travels to and reaches the first position. Similarly, the port member snaps over to the closed position when the actuator member travels to and reaches the second position.
In some exemplary embodiments, the actuator member and the port member will rotate about a common axis. For example, the actuator member may be generally cup-shaped, with the port member being concentrically positioned in the actuator member. Moreover, a bearing element may interpose the actuator member and the port member to facilitate relative rotation therebetween.
Often, the port member may be configured as a disc-like plate. In such embodiments, the port member may be juxtaposed in face-to-face contact with a surface defining a first flow port. Moreover, embodiments are contemplated in which the first flow passage is formed by a groove defined in a surface of the port member. Alternatively, the first flow passage may be formed as a hole defined in and extending through the port member.
Still further aspects of the present invention are achieved by a valve comprising a surface defining a first flow port. An actuator member rotatable about an axis of rotation is also provided. The valve further comprises a port member defining a first flow passage. The port member is rotatable about the axis of rotation to move the first flow passage in and out of registry with the first flow port. Also provided is a mechanism interconnecting the actuator member and the port member such that rotation of the actuator member will cause selective rotation of the port member.
In some exemplary embodiments, the port member further defines a second flow passage and the surface further defines a second flow port. Embodiments are contemplated in which the second flow passage will be in registry with the second flow port when the flow passage is out of registry with the first flow port.
Additional aspects of the invention are achieved by a method of switching between a first port and a second port. One step of the method involves rotating an actuator member from a first position to a second position. In response to the actuator member traveling to and reaching the second position, a port member is rotated in a snap over manner to a position that blocks flow into the first port while allowing flow into the second port. In response to the actuator member traveling to and reaching the first position, the port member is rotated in a snap over manner to a position that blocks flow into the second port while allowing flow into said first port.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.